"Generally, since 2007, there have been significant advances in forensic testing," Kathleen Zellner told 'Dateline NBC.'

Steven Avery's new lawyer believes that the subject of Netflix's popular docuseries Making a Murderer still has a good chance of being exonerated.

Kathleen Zellner, who spoke to Dateline NBC on Friday night in her first televised interview since taking Avery's case, said that she believes that Avery is innocent and that developments in scientific testing may be the proof her client needs.

"Generally, since 2007, there have been significant advances in forensic testing," Zellner told Dateline's Andrea Canning. "Am I going to tell you exactly what it is? I am not. But it's been a long time. There was a lot of evidence that wasn't tested."

Avery was convicted of the 2005 murder of 25-year-old Teresa Halbach, and his case has become a cultural sensation since Making a Murderer premiered in December.

Dateline, which promoted the episode as "Two Sides of the Steven Avery Case," also spoke to former District Attorney Ken Kratz, who prosecuted Avery.

"Steven Avery's guilty and deserves to be right where he is," Kratz told Dateline.

One of Avery's lawyers from 2005, Jerry Buting, said that he stands by his defense.

"From the evidence I've looked at I think he is innocent," Buting told Dateline. "I think he certainly was not guilty beyond a reasonable doubt under the evidence that was presented."

Although Avery's 2005 defense team argued that physical evidence pointed to a possible framing, and Zellner argues that scientific evidence could still exonerate her client, Kratz stand firm in his opinion.

"With any one of these facts, you can come up with a 'what-if' scenario," he said. "But at some point this conspiracy theory collapses under its own weight."